A color image display apparatus employs a CRT, an LCD (Liquid Crystal Device), a DLP (Digital Light Processing Device), a PDP, or the like.
In these color image display devices, three primary colors of red, green and blue are used as the fundamental colors, but in some of LCD displays and DLP projectors, white may be added to enhance the luminosity (e.g., refer to Japanese Patent Laid-Open No. 5-241551).
The entire disclosure of the above patent document is incorporated herein by reference in its entirety.
For example, in a one-chip DLP data projector of field sequential type, a full color image display is made using a four-color color wheel of red, green, blue and white (e.g., refer to A. Kunzman, G. Pettitt, “White Enhancement for Color-Sequential DLP”, SID International Symposium Digest of Technical Papers”, U.S.A., SID (Society for Information Display), May 1998, Vol. 29, pp. 121-124).
The entire disclosure of the above non-patent document is incorporated herein by reference in its entirety.
Such one-chip DLP data projector can improve the luminosity and contrast and reduce power consumption of the lamp.
Referring chiefly to FIG. 10 that is a block diagram of a conventional color image processing apparatus, the configuration and operation of the conventional color image processing apparatus will be more specifically described below.
The conventional color image processing apparatus displays a full color image using a liquid crystal pixel 5 having a red pixel 1 for making the red display, a green pixel 2 for making the green display, a blue pixel 3 for making the blue display and a white pixel 4 for making the white display, as shown in FIG. 11 that is an explanatory diagram of the conventional liquid crystal pixel 5.
A white signal generation circuit 1000 generates a white signal of 8 bitsW=min(Rin,Gin,Bin),  (Formula 1)based on an input red signal Rin of 8 bits for making the red display to be inputted, an input green signal Gin of 8 bits for making the green display to be inputted, and an input blue signal Bin of 8 bits for making the blue display to be inputted.
In this manner, in the conventional color image processing apparatus, the white signal W is generated to add white to enhance the luminosity.
However, the present inventor has noticed that the conventional color image display using the red display, green display, blue display, and white display may cause a sense of incompatibility in the appearance of the colors of yellow, cyan and magenta.
More specifically, the present inventor has made sure that particularly yellow remarkably tends to look darker among yellow, cyan and magenta.